what went wrong?

I was just compiling my nowhere-near-good map (currently in "block" stage) and i wanted to get in and see how some spots worked (Rocket jumps, stairs, etc). when i pressed f9 everything worked until i got in the map. i picked spy and this happened!

yay, i can answer something!
anyways...that error message comes up when you enter the unmapped abyss

so...if it comes up at the start...id assume that you have not created a team spawn and your origin isn't within the map?
so...either make a team spawn or see if there are any errors with your current one

Grab the entity tool (looks like a lightbuld on the right hand side) then on the left hand side there is a drop down box, it should default to info_teamspawn, then click in the 3d view of your map where you want it (THEN MAKE SURE ITS 16-32 UNITS OFF THE GROUND OTHERWISE THE PROBLEM WILL NOT GO AWAY)
That tool is also how you add models and lights.

I'd first suggest going through this - HERE - as this site isnt realyl the best place for an introduction to hammer, more of an intro to TF2 mapping for those that kinda already know hammer.